MINNEAPOLIS — The Minnesota Court of Appeals ruled Monday that a state law that makes it a crime to stalk someone by telephone is unconstitutional because it’s too broad.

The ruling overturns the conviction of a man who authorities say repeatedly left threatening messages for Rice County Sheriff’s Department and Social Services Department workers in 2016 and 2017.

Jason Peterson had called the Rice County sheriff, child protection workers, and others to complain about a 2002 family law case that changed his child custody and visitation. His messages contained profanity and left employees feeling frightened, prosecutors said. A jury convicted Peterson of two counts of stalking by telephone and he was sentenced to serve a year in jail.

Peterson argued that his convictions should be reversed because the statute criminalizing phone stalking unconstitutionally restricts free speech. The appeals court agreed and invalidated the statute.

Rice County Attorney John Fossum said the decision is not what the state expected. He said the state will review the ruling more carefully and determine whether or not it’s appropriate to appeal to the Minnesota Supreme Court.

The appeals court found that Minnesota’s stalking-by-telephone statute is similar to the state’s stalking-by-mail statute, which the state Supreme Court struck down because it was too broad and prohibited and chilled protected expression.

The appeals court said the phone stalking statute also criminalizes a substantial amount of protected speech and that there was no way for the court to narrow it. It said that under current law, a person could be charged for repeatedly calling a business to complain about pollution, or a worried parent could be charged for repeatedly texting a child — even if they don’t intend to frighten or intimidate the people they were calling.